After deciding on this setting for my first scene, I've moved on from my first colour test to these thumbnails, using the same image but manipulating it in different ways.
Thumbnails 36 - 39, using the unfinished test from before, were adjustments in the saturation and exposure, I think I'm most pleased with the first attempt, 36.
40 - 47 were light tests, introducing the idea of a wall of glass. I'm not liking thumbnails 40 to 43, mainly because of the colour itself, a softer blue/green like 46/47 seems to have a better effect on the overall scene. 44 and 45 look good but seem to lose the idea of being underwater.
The last row, 48 - 51 is tests where both walls are lined with books, I noticed right away that the scene becomes a lot more closed in, almost claustrophobic, without the large light source of the window and I'm not sure if that's something I want for my piece.